U.S. patent number 5,486,271 [Application Number 08/320,527] was granted by the patent office on 1996-01-23 for process for preparing perfluoroalkanesulfonyl fluorides.
This patent grant is currently assigned to Minnesota Mining and Manufacturing Company. Invention is credited to John C. Hansen, Herward A. Vogel.
United States Patent |
5,486,271 |
Hansen , et al. |
January 23, 1996 |
Process for preparing perfluoroalkanesulfonyl fluorides
Abstract
A process for preparing perfluoroalkanesulfonyl fluorides, e.g.,
perfluoromethanesulfonyl fluoride, is described which comprises
electrochemically fluorinating in the presence of anhydrous
hydrogen fluoride mono-, di- or tri- alkylsulfonyl alkyl esters or
amides, or mono-, bis- or tris- alkylsulfonyl alkanes or
disulfones. The process can be used to prepare
perfluoroalkanesulfonyl fluorides in good yield and can be both
more electrically-efficient and more fluorine-efficient than the
conventional preparative method involving the electrochemical
fluorination of hydrocarbon alkanesulfonyl halides.
Inventors: |
Hansen; John C. (Lakeland,
MN), Vogel; Herward A. (St. Paul, MN) |
Assignee: |
Minnesota Mining and Manufacturing
Company (Saint Paul, MN)
|
Family
ID: |
23246830 |
Appl.
No.: |
08/320,527 |
Filed: |
October 11, 1994 |
Current U.S.
Class: |
205/430 |
Current CPC
Class: |
C07C
303/22 (20130101); C25B 3/28 (20210101); C07C
303/22 (20130101); C07C 309/80 (20130101) |
Current International
Class: |
C07C
303/22 (20060101); C07C 303/00 (20060101); C25B
3/00 (20060101); C25B 3/08 (20060101); C07C
309/00 (20060101); C07C 309/80 (20060101); C25B
003/00 (); C25B 003/08 () |
Field of
Search: |
;204/59R,59F,81 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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582192 |
|
Feb 1994 |
|
EP |
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2-99586 |
|
Dec 1991 |
|
JP |
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Other References
Ser. No. 08/085,540 filed Jun. 30, 1993 to Behr. .
Willis, C. J., "Inorganic Analogues of Olefins" Thesis Cambridge
University, pp. 32-43, 110-111 Sep. (1958). .
March, J., Advanced Organic Chemistry, Third Edition, John Wiley
& Sons, New York, pp. 358, 363, 376, 411, 445, and 1089 No
Month (1985). .
Farng and Kice, "Substituted Reactions of Alkanesulfonyl
Derivitives," J. Am. Chem. Soc. No Month 1981, 103, 1137-1145.
.
Fluorine Chemistry, edited by J. H. Simons, pub. No Month 1950
Academic Press, Inc., New York, vol. 1, pp. 416-418. .
Gard et al., "New Perfluoro and Perfluoralkoxy Sulfonyl Fluorides
Part V. Fluorination Studies," Journal of Fluorine Chemistry, 55,
pp. 313-321, (1991) No Month. .
Stang, P. J. and White, M. J., "Trific Acid and It's Derivatives,"
Aldrichima Acta, vol. 16, pp. 15-22 (1983) No Month. .
Novikova et al., "Synthesis of trifluoromethyl sulfonic acid
fluoride by direct gas-phase fluorination of (fluorosulphonyl)
difuoroacetic acid fluoride," Journal of Fluorine Chemistry, vol.
58, Nos. 2-3, Aug.-Sep. 1992, p. 326. .
Rozhkov, I. N., "Anodic Fluorination," Organic Electrochemistry,
Second Edition, Marcel Dekker, Inc., New York and Basel, pp.
803-825 (1983) No Month. .
Preparation, Properties, and Industrial Applications of
Organofluorine Compounds, Banks, ed., John Wiley & Sons, New
York, pp. 37-43, (1982) No Month. .
Howells et al., "Trifluoromethanesulfonic Acid and Derivatives,"
Chemical Reviews, vol. 77, Feb. 1977, pp. 69-92. .
Hollitzer et al., "The Electrochemical Perfluorination (ECPF) Of
Propanesulfonyl Fluorides, Part I. Preparation and ECPF Of
1-Propanesulfonyl Fluoride and 1,3-Propanedisulfonyl Difloride,"
Journal of Fluorine Chemistry, 35, pp. 329-341, (1991) No Month.
.
Volkov, N. D., et al., "Preparation of Halodifluoromethanesulfonic
Acid Derivatives," Synthesis, pp. 972-975 (1979) No Month. .
Clark, "Perfluoroalkyl Derivatives of the Elements," Advances in
Fluorine Chemistry, vol. 3, pp. 19, 25-29, 55-56, Butterworths,
London (1963) No Month. .
Sokol'skii, G. A. and Dmitriev, M. A., "Electrochemical
Fluorination of Methyl Chlorosulfonate," Zhurnal Obshchei Khimii,
vol. 31, No. 3, pp. 706-710, (Mar. 1961). .
Sokol'skii, G. A. and Dmitriev, M. A.
"Hexafluorodimethylsulfonate," Zhurnal Obshchei Khimii, vol. 31,
No. 4, pp. 1107-1110, (Apr. 1961). .
Haszeldine, R. J. and Kidd, J. M., "Perfluoroalkyl Derivatives of
Sulphur . . . ," J. of the Chemical Society, pp. 2901-2910 May
(1955)..
|
Primary Examiner: Niebling; John
Assistant Examiner: Wong; Edna
Attorney, Agent or Firm: Little; Douglas B. Griswold; Gary
L. Kirn; Walter N.
Claims
What is claimed is:
1. A process of preparing perfluoroalkanesulfonyl fluorides
comprising electrochemically fluorinating in the presence of
anhydrous hydrogen fluoride a compound of the formula
(RSO.sub.2).sub.n X wherein R is alkyl of 1 to 20 carbon atoms in
which the carbon chain may be interrupted by one or more ether
oxygen atoms;
(a) n is 1, and X is --R.sup.i, --OR.sup.i, --NR.sup.ii R.sup.iii
or --SO.sub.2 R, in which R is as defined above; R.sup.i is R;
R.sup.ii and R.sup.iii are each independently hydrogen or alkyl of
1 to 8 carbon atoms in which the carbon chain may be interrupted by
one or more ether oxygen atoms, or when taken together with the
nitrogen atom form a five to seven membered heterocyclic ring
optionally interrupted by a heteroatom selected from nitrogen,
oxygen and sulfur; with the proviso of excluding dimethylsulfone
and diethylsulfone;
(b) n is 2, and X is --R.sup.i --, --OR.sup.i --, --OR.sup.iv O--
or ##STR5## in which R.sup.i is an alkylene of 1 to 20 carbon atoms
optionally containing one or more ether oxygen atoms; R.sup.iv is
alkylene of 1 to 8 carbon atoms; R.sup.ii is hydrogen or alkyl of 1
to 8 carbon atoms in which the carbon chain may be interrupted by
one or more ether oxygen atoms, or
(c) n is 3, and X is ##STR6## in which R is as defined above but
with 3 bond sites, with the proviso that the electrochemical
fluorination is conducted under the following conditions: current
density of about 10 to 600 amps per square meter of anode surface;
and a temperature sufficient to maintain a boiling hydrogen
fluoride liquid phase during the fluorination.
2. The process of claim 1, wherein R is alkyl of 1-8 carbon atoms
in which the carbon chain may be interrupted by one or more ether
oxygen atoms.
3. The process of claim 2, wherein n is 1; R.sup.i is R, and
R.sup.ii and R.sup.iii are each independently hydrogen or alkyl of
1 to 4 carbon atoms or when taken together with the nitrogen atom
form a 5- or 6- membered heterocyclic ring optionally interrupted
by a heteroatom selected from nitrogen, oxygen and sulfur.
4. The process of claim 2, wherein n is 2; R.sup.i is an alkylene
group of 1 to 4 carbon atoms optionally containing an ether oxygen
atom, and R.sup.ii is hydrogen or alkyl of 1 to 4 carbon atoms.
5. A process of preparing perfluoromethanesulfonyl fluoride
comprising electrochemical fluorination in the presence of
anhydrous hydrogen fluoride of a compound of the formula (CH.sub.3
SO.sub.2).sub.n X wherein
(a) n is 1, and X is --R.sup.i, --OR.sup.i, --NR.sup.ii R.sup.iii
or --SO.sub.2 R, in which R is alkyl of 1 to 20 carbon atoms in
which the carbon chain may be interrupted by one or more ether
oxygen atoms; R.sup.i is alkyl of 2 to 20 carbon atoms in which the
carbon chain may be interrupted by one or more ether oxygen atoms;
R.sup.ii and R.sup.iii are each independently hydrogen or alkyl of
1 to 8 carbon atoms in which the carbon chain may be interrupted by
one or more ether oxygen atoms, or when taken together with the
nitrogen atom form a five to seven membered heterocyclic ring
optionally interrupted by a heteroatom selected from nitrogen,
oxygen and sulfur;
(b) n is 2, and X is --R.sup.i --, --OR.sup.i --, --OR.sup.iv O--
or ##STR7## in which R.sup.i is an alkylene of 1 to 20 carbon atoms
optionally containing one or more ether oxygen atoms; R.sup.iv is
alkylene of 1 to 8 carbon atoms; R.sup.ii is hydrogen or alkyl of 1
to 8 carbon atoms in which the carbon chain may be interrupted by
one or more ether oxygen atoms, or
(c) n is 3, and X is ##STR8## in which R is as defined above but
with 3 bond sites with the proviso that the electrochemical
fluorination is conducted under the following conditions: current
density of about 10 to 600 amps per square meter of anode surface;
and a temperature sufficient to maintain a boiling hydrogen
fluoride liquid phase during the fluorination.
6. The process of claim 5, wherein n is 1; R is alkyl of 1-8 carbon
atoms; R.sup.i is alkyl of 2 to 8 carbon atoms optionally
containing an ether oxygen atom, and R.sup.ii and R.sup.iii are
each independently hydrogen or alkyl of 1 to 4 carbon atoms or when
taken together with the nitrogen atom form a 5- or 6- membered
heterocyclic ring optionally interrupted by a heteroatom selected
from nitrogen, oxygen and sulfur.
7. The process of claim 5, wherein n is 2; R.sup.i is an alkylene
of 1 to 8 carbon atoms optionally containing an ether oxygen atom;
R.sup.iv is alkylene of 1 to 4 carbon atoms; and R.sup.ii is
hydrogen or alkyl of 1 to 4 carbon atoms.
8. The process of claim 6, wherein the compound is
dimethyldisulfone.
9. The process of claim 6, wherein the compound is selected from
the group consisting of methyl methanesulfonate, butyl
methanesulfonate, octyl methanesulfonate, isopropyl
methanesulfonate and morpholinomethane sulfonamide.
10. The process of claim 7 wherein the compound is N, N-
bis-methane sulfonimide.
11. A method of preparing perfluoroalkanesulfonyl fluorides which
comprises using in an electrochemical fluorination process, a
compound of the formula (RSO.sub.2).sub.n X wherein R is alkyl of 1
to 20 carbon atoms in which the carbon chain may be interrupted by
one or more ether oxygen atoms;
(a) n is 1, and X is --R.sup.i, --OR.sup.i, --NR.sup.ii R.sup.iii
or --SO.sub.2 R, in which R is as defined above; R.sup.i is R;
R.sup.ii and R.sup.iii are each independently hydrogen or alkyl of
1 to 8 carbon atoms in which the carbon chain may be interrupted by
one or more ether oxygen atoms, or when taken together with the
nitrogen atom form a five to seven membered heterocyclic ring
optionally interrupted by a heteroatom selected from nitrogen,
oxygen and sulfur; with the proviso of excluding dimethylsulfone
and diethylsulfone;
(b) n is 2, and X is --R.sup.i --, --OR.sup.i --, --OR.sup.iv O--
or ##STR9## in which R.sup.i is an alkylene of 1 to 20 carbon atoms
optionally containing one or more ether oxygen atoms; R.sup.iv is
alkylene of 1 to 8 carbon atoms; R.sup.ii is hydrogen or alkyl of 1
to 8 carbon atoms in which the carbon chain may be interrupted by
one or more ether oxygen atoms, or
(c) n is 3, and X is ##STR10## in which R is as defined above but
with 3 bond sites with the proviso that the electrochemical
fluorination is conducted under the following conditions: current
density of about 10 to 600 amps per square meter of anode surface;
and a temperature sufficient to maintain a boiling hydrogen
fluoride liquid phase during the fluorination.
12. The method of claim 11, wherein R is alkyl of 1-8 carbon atoms
in which the carbon chain may be interrupted by one or more ether
oxygen atoms.
13. The method of claim 12, wherein n is 1; R.sup.i is R, and
R.sup.ii and R.sup.iii are each independently hydrogen or alkyl of
1 to 4 carbon atoms or when taken together with the nitrogen atom
form a 5- or 6- membered heterocyclic ring optionally interrupted
by a heteroatom selected from nitrogen, oxygen and sulfur.
14. The method of claim 12, wherein n is 2; R.sup.i is alkylene of
1 to 4 carbon atoms optionally containing an ether oxygen atom, and
R.sup.ii is hydrogen or alkyl of 1 to 4 carbon atoms.
15. A method of preparing perfluoromethanesulfonyl fluoride which
comprises using in an electrochemical fluorination process, a
compound of the formula (CH.sub.3 SO.sub.2).sub.n X wherein
(a) n is 1, and X is --R.sup.i, --OR.sup.i, --NR.sup.ii R.sup.iii
or --SO.sub.2 R, in which R is alkyl of 1 to 20 carbon atoms in
which the carbon chain may be interrupted by one or more ether
oxygen atoms; R.sup.i is alkyl of 2 to 20 carbon atoms in which the
carbon chain may be interrupted by one or more ether oxygen atoms;
R.sup.ii and R.sup.iii are each independently hydrogen or alkyl of
1 to 8 carbon atoms in which the carbon chain may be interrupted by
one or more ether oxygen atoms, or when taken together with the
nitrogen atom form a five to seven membered heterocyclic ring
optionally interrupted by a heteroatom selected from nitrogen,
oxygen and sulfur;
(b) n is 2, and X is --R.sup.i --, --OR.sup.i --, --OR.sup.iv O--
or ##STR11## in which R.sup.i is an alkylene of 1 to 20 carbon
atoms optionally containing one or more ether oxygen atoms;
R.sup.iv is alkylene of 1 to 8 carbon atoms; R.sup.ii is hydrogen
or alkyl of 1 to 8 carbon atoms in which the carbon chain may be
interrupted by one or more ether oxygen atoms, or
(c) n is 3, and X is ##STR12## in which R is as defined above but
with 3 bond sites with the proviso that the electrochemical
fluorination is conducted under the following conditions: current
density of about 10 to 600 amps per square meter of anode surface;
and a temperature sufficient to maintain a boiling hydrogen
fluoride liquid phase during the fluorination.
16. The method of claim 15 wherein n is 1; R is alkyl of 1-8 carbon
atoms; R.sup.i is alkyl of 2 to 8 carbon atoms optionally
containing an ether oxygen atom, and R.sup.ii and R.sup.iii are
each independently hydrogen or alkyl of 1 to 4 carbon atoms or when
taken together with the nitrogen atom form a 5- or 6- membered
heterocyclic ring optionally interrupted by a heteroatom selected
from nitrogen, oxygen and sulfur.
17. The method of claim 15, wherein n is 2; R.sup.i is an alkylene
of 1 to 4 carbon atoms optionally containing an ether oxygen atom;
R.sup.iv is alkylene of 1 to 4 carbon atoms; and R.sup.ii is
hydrogen or alkyl of 1 to 4 carbon atoms.
18. The method of claim 16, wherein the compound is dimethyl
disulfone.
19. The method of claim 16, wherein the compound is selected from
the group consisting of methyl methanesulfonate, butyl
methanesulfonate, octyl methanesulfonate, isopropyl
methanesulfonate and morpholinomethane sulfonamide.
20. The method of claim 17, wherein the compound is N, N-
bis-methane sulfonimide.
Description
FIELD OF THE INVENTION
This invention relates to a process for preparing
perfluoroalkanesulfonyl fluorides by electrochemical
fluorination.
BACKGROUND OF THE INVENTION
Perfluoroalkanesulfonyl fluorides are useful as starting materials
for the preparation of a variety of useful compounds. For example,
perfluoromethanesulfonyl fluoride can be used to prepare
perfluoromethanesulfonic acid, which has been reported to be the
strongest of all known monoprotic organic acids. (See R. D. Howells
and J. D. McCown, Chem. Rev., 77, 69 (1977).)
Perfluoroalkanesulfonyl fluorides can also be utilized to prepare
perfluoroalkanesulfonamides (which are useful as herbicides,
antimicrobials, and pharmaceuticals) and salts such as lithium
perfluoroalkanesulfonates and lithium bis
(perfluoroalkanesulfonyl)imides (which are useful as electrolyte
salts for battery applications). (See P. J. Stang and M. R. White,
Aldrichimica Acta, 16, 15 (1983) and Kirk-Othmer Encyclopedia of
Chemical Technology, Fourth Edition, Volume 3, page 1017, John
Wiley & Sons, New York, (1992).)
Perfluoroalkanesulfonyl fluorides have been prepared from a variety
of different starting materials by such methods as electrochemical
fluorination, direct fluorination, and photolysis.
For example, U.S. Pat. No. 2,732,398 (Brice et al.) discloses the
preparation of perfluoroalkanesulfonyl fluorides by the
electrochemical fluorination (ECF) in anhydrous liquid hydrogen
fluoride of the corresponding hydrocarbon alkanesulfonyl
halides.
J. Fluorine Chem. 58, 326 (1992) (M. Novikova et al.) describes the
preparation of perfluoromethanesulfonyl fluoride by direct
gas-phase fluorination of (fluorosulfonyl)difluoroacetyl
fluoride.
Syntheses, 972 (1979) (N. D. Volkov et al.) discloses the
preparation of halodifluoromethanesulfonyl fluorides by photolysis
of the corresponding 2-halo-2-oxodifluoroethanesulfonyl
fluorides.
SUMMARY OF THE INVENTION
Accordingly, this invention provides a process for preparing
perfluoroalkanesulfonyl fluorides comprising electrochemically
fluorinating in the presence of anhydrous hydrogen fluoride a
compound of the Formula I
wherein R is alkyl of 1 to 20 carbon atoms in which the carbon
chain may be interrupted by one or more ether oxygen atoms;
(a) n is 1, and X is --R.sup.i, --OR.sup.i, --NR.sup.ii R.sup.iii
or --SO.sub.2 R, in which R is as defined above; R.sup.i is R;
R.sup.ii and R.sup.iii are each independently hydrogen or alkyl of
1 to 8 carbon atoms in which the carbon chain may be interrupted by
one or more ether oxygen atoms, or when taken together with the
nitrogen atom form a five to seven membered heterocyclic ring
optionally interrupted by a heteroatom selected from nitrogen,
oxygen and sulfur; with the proviso of excluding dimethylsulfone
and diethylsulfone;
(b) n is 2, and X is --R.sup.i --, --OR.sup.i --, --OR.sup.iv O--
or ##STR1## in which R.sup.i is R or alkylene of 1 to 8 carbon
atoms optionally containing one or more ether oxygen atoms as
defined above; R.sup.iv is alkylene of 1 to 8 carbon atoms;
R.sup.ii is hydrogen or alkyl of 1 to 8 carbon atoms in which the
carbon chain may be interrupted by one or more ether oxygen atoms,
or
(c) n is 3, and X is ##STR2##
A preferred aspect of this invention is using a compound of the
formula (CH.sub.3 SO.sub.2).sub.n X for preparing perfluoromethane
sulfonyl fluorides. Most preferably, dimethyl disulfone is
utilized.
The process of the invention provides a route to
perfluoroalkanesulfonyl fluorides which can be both more
electrically-efficient and more fluorine-efficient than the
conventional route involving the electrochemical fluorination of
hydrocarbon alkanesulfonyl halides. The compounds of Formula I
possess significant advantages as feed materials in the
electrochemical fluorination process over the hydrocarbon alkane
sulfonyl halides, e.g. methane sulfonyl fluoride, and dimethyl
sulfone. Methane sulfonyl fluoride is highly toxic and dimethyl
sulfone generates, besides perfluoromethanesulfonyl fluoride
(PMSF), large amounts of low boiling CF.sub.4 gas which is a
difficult to recover, low commercial value by-product.
Dimethylsulfone and its solution in anhydrous HF create severe
metal corrosion. As a high melting point solid, dimethylsulfone
presents handling problems in the feed process.
The compounds of Formula I, e.g. alkyl methane sulfonates, are
easier to handle in the electrochemical fluorination and generate
perfluoromethanesulfonyl fluoride and a perfluoroalkane (and
carboxylic acid fluorides when the raw material is a sulfonate
ester) as a co-product. The co-products are often more readily
recovered and have good commercial value. For example in the
electrochemical fluorination of octyl methanesulfonate,
perfluoromethanesulfonyl fluoride and perfluorooctane are
recovered. The latter is also a valuable product used, for example,
as a thermal transfer media, solvent, refrigerant, etc.
Another advantage of using the compounds of Formula I in the
electrochemical fluorination process of the present invention is
the fact that carbon-sulfur bond cleavage (which would provide a
highly toxic, undesirable product, SO.sub.2 F.sub.2) does not
predominate.
The process of the invention provides perfluoroalkanesulfonyl
fluorides in good yield by the electrochemical fluorination of the
compounds of Formula I which are commercially available or can be
prepared from readily available industrial starting materials. Thus
raw materials are not wasted making by-products of little value. In
addition, electricity is better utilized because of the good
yields.
DETAILED DESCRIPTION OF THE INVENTION
The compounds of the present invention utilized in the
electrochemical fluorination process are those of Formula I defined
above.
The term "alkyl" is followed by the designated numbers of carbon
atoms in a hydrocarbon chain and includes a straight or branched
aliphatic hydrocarbon radical within the numbered range, e.g.
methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl,
tert-butyl, hexyl, octyl, decyl, dodecyl, and the like.
The term "alkylene" is a hydrocarbon radical of the formula
--(CH.sub.2).sub.n -- where n may vary from 1 to 8 unless
designated otherwise and includes, for example, methylene,
ethylene, propylene, butylene, and the like.
The term "five to seven membered heterocyclic ring optionally
interrupted by a heteroatom selected from nitrogen, oxygen and
sulfur" includes, for example, pyrrolidine, piperidine,
homopiperidine, piperazine, morpholine, thiomorpholine, and the
like.
A preferred embodiment of compounds of Formula I defined above and
utilized in the process of the invention is a compound wherein R is
alkyl of 1 to 8 carbon atoms in which the carbon chain may be
interrupted by one or more ether oxygen atoms.
A more preferred embodiment of Formula I is a compound wherein n is
1; X is as defined above, except R.sup.i is R in which R is alkyl
of 1 to 8 carbon atoms in which the carbon chain may be interrupted
by one or more ether oxygen atoms, and R.sup.ii and R.sup.iii are
each independently hydrogen or alkyl of 1 to 4 carbon atoms or when
taken together with the nitrogen atom form a 5- or 6- membered
heterocyclic ring optionally interrupted by a heteroatom selected
from nitrogen, oxygen and sulfur.
Another more preferred embodiment of Formula I is a compound
wherein n is 2; X is as defined above; R.sup.i is R, in which R is
alkyl of 1 to 8 carbon atoms in which the carbon chain may be
interrupted by one or more ether oxygen atoms, or alkylene of 1 to
8, more preferably 1 to 4 carbon atoms optionally containing an
ether oxygen atom, and R.sup.ii is hydrogen or alkyl of 1 to 8,
more preferably 1 to 4 carbon atoms.
When one of the desired products in the electrochemical
fluorination process is perfluoromethanesulfonyl fluoride, the
precursor compound utilized is of the Formula II
wherein n is 1, and X is --R.sup.i, --OR.sup.i, --NR.sup.ii
R.sup.iii or --SO.sub.2 R, in which R is alkyl of 1 to 20 carbon
atoms in which the carbon chain may be interrupted by one or more
ether oxygen atoms; R.sup.i is alkyl of 2 to 20 carbon atoms in
which the carbon chain may be interrupted by one or more ether
oxygen atoms; R.sup.ii and R.sup.iii are each independently
hydrogen or alkyl of 1 to 8 carbon atoms in which the carbon chain
may be interrupted by one or more ether oxygen atoms, or when taken
together with the nitrogen atom form a five to seven membered
heterocyclic ring optionally interrupted by a heteroatom selected
from nitrogen, oxygen and sulfur;
n is 2, and X is --R.sup.i --, --OR.sup.i --, --OR.sup.iv O-- or
##STR3## in which R.sup.i is R or alkylene of 1 to 8 carbon atoms
optionally containing one or more ether oxygen atoms; R.sup.iv is
alkylene of 1 to 8 carbon atoms; and R.sup.ii is hydrogen or alkyl
of 1 to 8 carbon atoms in which the carbon chain may be interrupted
by one or more ether oxygen atoms, or
n is 3, and X is ##STR4##
A preferred embodiment of a compound of Formula II utilized in the
process of the invention is a compound wherein n is 1; X is as
defined above, in which R is alkyl of 1-8 carbon atoms; R.sup.i is
alkyl of 2 to 8 carbon atoms optionally containing an ether oxygen
atom, and R.sup.ii and R.sup.iii are each independently hydrogen or
alkyl of 1 to 4 carbon atoms or when taken together with the
nitrogen atom form a 5- or 6-membered heterocyclic ring optionally
interrupted by a heteroatom selected from nitrogen, oxygen and
sulfur.
Another preferred embodiment of Formula II is a compound wherein n
is 2; X is as defined above; R.sup.i is R, in which R is alkyl of
1-8 carbon atoms, or alkylene of 1 to 4 carbon atoms optionally
containing an ether oxygen atom; R.sup.iv is alkylene of 1 to 4
carbon atoms; and R.sup.ii is hydrogen or alkyl of 1 to 4 carbon
atoms.
Particularly valuable precursor compounds utilized in the process
of this invention include:
isobutyl methanesulfonate,
octyl methanesulfonate,
isopropyl methanesulfonate,
butyl methanesulfonate,
methyl methanesulfonate,
methyl butyl sulfone
methyl octyl sulfone
methane sulfonamide,
morpholino-methane sulfonamide,
tris(methyl sulfonyl) methane,
ethylene glycol dimethylsulfonate,
1,1 bis(methyl sulfonyl) butane,
hexyl octyl sulfone,
bis(6-hexyl sulfonyl) methane,
bis(8-octyl sulfonyl) methane,
methyl ethanesulfonate,
ethyl ethanesulfonate,
ethyl methanesulfonate,
bis(methyl sulfonyl) methane,
N, N-bis-methane sulfonimide, and
dimethyl disulfone.
Compounds of Formulas I and II are either commercially available or
can be prepared by known methods from commercially available
starting materials. Thus, for example, sulfonate esters can be
prepared by the reaction of an alcohol with a sulfonic acid or
sulfonyl halide as described in March, Advanced Organic Chemistry,
John Wiley & Sons, New York, 1985, p. 358.
Sulfonamides may be prepared by N-alkylation of sulfonamides
(March, ibid., p. 376 or p. 411), or by the reaction of an amine
with a sulfonic acid, ester or sulfonyl halide (March, ibid., p.
445).
Sulfones may be prepared by the reaction of an alkyl halide with a
sulfinate (March ibid., p. 363) or by the oxidation of sulfides or
sulfoxides (March ibid., p. 1089).
Disulfones may be prepared by the procedure described by Farng and
Kice in J. Am. Chem. Soc., 1981, 103, 1137-1145.
The electrochemical fluorination of the above-described precursor
compounds can be carried out by introducing, e.g., by pumping, at
least one precursor compound of Formula I and/or Formula II to a
Simons electrochemical fluorination cell containing anhydrous
hydrogen fluoride (or to which anhydrous hydrogen fluoride is
simultaneously or subsequently added). The Simons electrochemical
fluorination cell is an electrolytic cell in which is suspended an
electrode pack comprising a series of alternating and
closely-spaced cathode plates (typically made of iron or nickel or
nickel alloy) and anode plates (typically made of nickel). The
electrodes are connected in parallel through electrode posts. The
cell body can be made of, for example, carbon steel, which may have
a coating of corrosion resistant material, and is usually provided
with a cooling jacket, a valved outlet pipe at the bottom through
which can be drained the settled liquid cell product ("drainings"),
a valved inlet pipe at the top of the cell for charging the cell
with the precursor compound(s) and liquid anhydrous hydrogen
fluoride, and an outlet pipe at the top of the cell for removing
gaseous cell products evolved in operation of the cell.
The gaseous stream leaving the cell can comprise HF, hydrogen,
OF.sub.2 (oxygen difluoride) and other gases. The outlet pipe can
be connected to a refrigerated condenser for condensing hydrogen
fluoride vapors and relatively hydrogen fluoride-insoluble
fluorochemical products. The resulting condensed materials can be
phase-separated, the fluorochemical products collected, and the
hydrogen fluoride returned to the cell. The gaseous stream from the
top of the cell may pass through a packed bed of catalyst (e.g.
silver or silver fluoride or aluminum support) in which HF is
removed. U.S. Pat. No. 2,519,983 contains a drawing of such a
Simons electrolytic cell and its appurtenances, and a description
and photographs of laboratory and pilot plant cells appear at pages
416-18 of Volume I of Fluorine Chemistry, edited by J. H. Simons,
published in 1950 by Academic Press, Inc., New York.
The Simons (ECF) cell can be operated at average applied direct
current cell voltages in the range of from about 4 to about 8 volts
(sufficiently high, but not so high as to generate free fluorine),
at current densities of from about 10 to about 600 amps/m.sup.2 of
active anode surface, preferably 20 to 300 amps/m.sup.2, at
substantially atmospheric or ambient pressure or higher, e.g. 207
KiloPascals (KPa), and at temperature ranging from below about
0.degree. C. to about 20.degree. C. or as high as about 60.degree.
C. (so long as the electrolytic solution remains liquid.) The cell
is run at boiling condition for the cell liquid but a liquid phase
is maintained. Temperature can be controlled by controlling back
pressure in the cell itself, by means of a back pressure control
valve on the gas outlet line. The initial amount of precursor
compound(s) in the anhydrous hydrogen fluoride can be, for example,
from about 5 to about 20 weight percent, and both the precursor
compound(s) and the anhydrous hydrogen fluoride can be replenished
from time to time.
If desired, a conventional conductivity additive, such as
dimethyldisulfide (DMDS), lithium fluoride, methyl acetate, sodium
fluoride, acetic anhydride, or an organic sulfur-containing
compound such as that described in U.S. Pat. Nos. 3,028,321
(Danielson), 3,692,643 (Holland), and 4,739,103 (Hansen), can be
added to the cell to increase the conductivity of the cell
contents. The amount of said additive can be, for example, from
about 1 to 20 percent by weight (based upon the weight of the
precursor compound(s)). In making higher molecular weight
fluoroalkanes, DMDS appears to be beneficial.
In the experiments made in developing this invention, gaseous ECF
reaction products were collected using condensers at -40.degree. C.
and decanter vessels. In collecting PMSF, collection traps cooled
with dry ice (solid CO.sub.2 at -78.degree. C.) and some with
liquid nitrogen (-196.degree. C.) were used. HF concentration was
typically in the range of 70 to 99 weight percent in the ECF
cell.
Other details of the Simons electrochemical fluorination process
and cell will be omitted here in the interest of brevity, and the
disclosures of such technology in the above-cited references to
such technology can be referred to for such detail, which
disclosures are incorporated herein by reference. ECF production
scale cells vary in size from small cells operating at currents of
from less than 100 amps to large cells which use 10,000 amps or
more.
The process of the invention can be carried out continuously
(continuously introducing precursor compound(s) to the cell and
continuously withdrawing liquid cell product), semi-continuously or
batchwise. The term semi-continuously can mean: continuously
introducing precursor until the total charge is complete, and then
reacting to the desired extent; or intermittently introducing
precursor in a number of aliquots. The continuous mode of operation
is preferred for large-scale operation, as it enables better
control of the operating variables. The level of liquid in the cell
is preferably controlled, and both HF and (RSO.sub.2).sub.n X can
be replenished during the reaction.
The desired perfluoroalkanesulfonyl fluoride product is preferably
recovered, for example, by condensation followed by
phase-separation into an upper hydrogen fluoride-containing phase
and a lower fluorochemical-containing phase (e.g., by use of a
decanter) and subsequent draining of the lower phase. The drainings
can be further purified, if desired, by passage through a column
containing sodium fluoride in order to remove any residual hydrogen
fluoride. In addition, low temperature distillation can be used to
isolate the desired fluorochemical products.
The perfluoroalkanesulfonyl fluoride products of the process are
useful as starting materials for the preparation of a variety of
compounds having utility, for example, as strong acids, herbicides,
pesticides, antimicrobials, pharmaceuticals, and as electrolyte
salts for battery or fuel cell applications.
This invention is further illustrated by the following examples,
but the particular materials and amounts thereof recited in these
examples, as well as other conditions and details, should not be
construed to limit this invention.
EXAMPLES
EXAMPLE 1
Electrochemical fluorination of METHYL METHANESULFONATE
An electrochemical fluorination cell of the type described in U.S.
Pat. No. 2,519,983 (Simons) was fitted, in series, with a
-40.degree. C. condenser, a -78.degree. C. condenser, and liquid
nitrogen condenser. The cell was charged with anhydrous HF and 615
g of methyl methane sulfonate was fed by a pump in a
semi-continuous manner over a period of 166 hours (average of 0.305
g/1.0 ampere-hour of current passed), while electrolyzing the
resulting solution using an average voltage of 6.5 volts at an
average current of 12.2 amps at 55.degree. C. and at a pressure of
0.21 MPa (30 psig). The gaseous products from the cell were passed
to the -40.degree. C. condenser where most of the HF condensed and
was returned to the cell. The fluorochemical products produced were
collected in the -78.degree. C. condenser and the liquid nitrogen
condenser. The collected product stream was analyzed using gas
chromatography and Fourier transform infrared spectroscopy to
determine product structures and yields.
Perfluoromethanesulfonyl fluoride (CF.sub.3 SO.sub.2 F) was
collected from the latter two condensers at an average rate of 15.5
g/50 ampere-hour (65% of theoretical yield based on current flow
(theo.)). COF.sub.2 was also collected, but the rate was not
determined.
EXAMPLE 2
Electrochemical fluorination of OCTYL METHANESULFONATE
Octyl methanesulfonate was electrochemically fluorinated as in
Example 1 with the addition of dimethyl disulfide as a conductivity
additive (10 wt % of the octyl methanesulfonate) at an average of
6.7 volts, an average 14.5 amps, an average of 52.degree. C. and
0.21 MPa (30 psig) control. CF.sub.3 SO.sub.2 F was produced at a
rate of about 0.042 g/1.0 ampere-hour of current passed (35%
theo.), based upon cleavage of the sulfur-oxygen bond. The other
major product formed was C.sub.8 F.sub.18.
EXAMPLE 3
Electrochemical fluorination of ISOPROPYL METHANESULFONATE
Isopropylmethane sulfonate was electrochemically fluorinated as in
Example 1 at 6.7 volts average, at 13.5 amps average current,
45.degree.-55.degree. C. and 0.17-0.21 MPa (25 to 30 psig) control.
Perfluoromethanesulfonyl fluoride was produced at 0.12 g to 0.15
g/1.0AH. (50% to 60% theo). C.sub.3 F.sub.8 was also produced at
0.13 g to 0.18 g/1.0 AH or about 43% to 60% theo. A minor amount of
unidentified fluorocarbons with boiling points above 60.degree. C.
was also produced.
EXAMPLE 4
Electrochemical fluorination of BUTYL METHANESULFONATE
Electrochemical fluorination as in Example 1 was carried out with
the addition of dimethyl disulfide as a conductivity additive (10
wt % of the octyl methanesulfonate) at about the same temperatures
and pressures, averaging 25 amps/ft..sup.2 (269a/m.sup.2) current
at 6.1 average volts and producing perfluoromethanesulfonyl
fluoride at 60% theo. or about 0.18 g/1.0 ampere-hour. The other
major cleavage product was C.sub.4 F.sub.10, also made at 0.18
g/1.0 ampere-hour (39% theo.). A minor amount of unidentified
fluorocarbons with boiling points above that of C.sub.4 F.sub.10
was also produced.
EXAMPLE 5
Electrochemical fluorination of METHYL BUTYL SULFONE
This was electrochemically fluorinated as in Example 1 at 5.6 volts
average, 13.8 amps average current, 0.14 MPa (20 psig) control and
about 45.degree. C. Perfluoromethanesulfonyl fluoride was produced
at about 20% theo. (0.041 g/1.9 ampere-hour) and C.sub.4 F.sub.10
at about 25% theo. (0.13 g/1.0 ampere-hour). In addition C.sub.4
F.sub.9 SO.sub.2 F was produced at about 7-8% theo. (0.0314 g/1.0
ampere-hour) and perfluoromethyl-butyl sulfone (CF.sub.3 SO.sub.2
C.sub.4 F.sub.9) was produced at about 10% theo. (0.033 g/1
ampere-hour).
EXAMPLE 6
Electrochemical fluorination of METHYL OCTYL SULFONE
This was electrochemically fluorinated as in Example 1 at 6.3 volts
average, 10.8 amps average current, an average of 0.10 MPa (15
psig) control and an average of about 40.degree. C.
Perfluoromethanesulfonyl fluoride was produced at 40% theo. or
0.054 g/ampere-hour. Perfluoroctane sulfonyl fluoride was produced
at 5% theo. or 0.0226 g/ampere-hour. Perfluorooctane was produced
at 41% theo. or 0.16 g/ampere-hour.
EXAMPLE 7
Electrochemical fluorination of METHANE SULFONAMIDE
450 g. Methane sulfonamide was dissolved in anhydrous HF and fed
(at an average rate of 0.143 g/1.0 (AH) ampere-hour)) to a 750 c.c.
volume electrochemical cell operating at an average of 16 amps at
5.5 volts, atmospheric pressure and about 20.degree. C.
The methane sulfonamide was fed by means of a gravity charger, an
apparatus for conveying liquids to a vessel at very small flow
rates. A gravity charger comprises essentially: a reservoir of the
raw material to be conveyed (methane sulfonamide in this case); a
tube connecting the reservoir to the ECF cell; a pressure
equalizing tube connecting the tops of the ECF cell and the
reservoir; and a lifting means capable of raising the reservoir
slowly to change the static head pressure difference between the
raw material in the reservoir and the liquid in the ECF cell. In
this case, the lifting means was an electric motor which drove a
threaded rod (the rotational speed of which was adjustable), which,
in turn, slowly advanced a mechanical means connected to the
reservoir. As the reservoir lifted, the slow increase in static
head caused the liquid raw material to flow into the ECF cell.
Perfluoromethanesulfonyl fluoride was produced at about 80% theo.
or 0.38 g/ampere-hour, with some minor cleavage to CF.sub.4,
SO.sub.2 F.sub.2 and SOF.sub.4 with the nitrogen lost as
NF.sub.3.
EXAMPLE 8
Electrochemical fluorination of MORPHOLINOMETHANESULFONAMIDE
Morpholino methanesulfonamide was electrochemically fluorinated
under the same operating conditions as Example 7 at 5.2 volts
average and 12.1 amps average current. Perfluoromethanesulfonyl
fluoride was produced at about 70% theo. or about 0.116
g/ampere-hour at a feed rate of about 0.155 g/ampere-hour.
Perfluoromorpholine was also made at about 77% theo.
EXAMPLE 9
Electrochemical fluorination of DIMETHYL DISULFONE
11.8 g Dimethyl disulfone was dissolved in anhydrous HF and then
fed (in three approximately equal aliquots by means of a syringe
system) into a small (about 180 cc. volume) cell semi-continuously.
The cell was run at 6.2 volts average, 2 amps average current,
atmospheric pressure and about 20.degree. C. The production rates
of perfluoromethanesulfonyl fluoride varied between 73% theo. and
88% theo. or 0.60 g/ampere-hour to 0.72 g/ampere-hour of current
passed. There were minor amounts of the cleavage products CF.sub.4,
CF.sub.3 H. SO.sub.2 F.sub.2 and SOF.sub.4.
EXAMPLE 10
Electrochemical fluorination of ETHYLENE GLYCOL
DIMETHANESULFONATE
CH.sub.3 SO.sub.3 CH.sub.2 CH.sub.2 O.sub.3 SCH.sub.3 was
fluorinated as in Example 1 at an average of 20 amps, an average
7.0 volts, 0.1 MPa (15 psig) control and 40.degree. C.
Perfluoromethanesulfonyl fluoride rates were about 15% theo. or
0.078 g/ampere-hour. In addition to the desired
perfluoromethanesulfonyl fluoride, other cleavage products
including COF.sub.2, SO.sub.2 F.sub.2, CF.sub.4, CO.sub.2, CF.sub.3
H and SOF.sub.4 were produced.
EXAMPLE 11
Electrochemical fluorination of BIS(METHYLSULFONYL)METHANE
This was fluorinated as in Example 1 at an average of 20 amps, an
average of 5.4 volts, 0.17MPa (25 psig) control and 50.degree. C.
Perfluoromethanesulfonyl fluoride was produced at about 40 to 50%
theo. 0.228 g/ampere-hour to 0.286 g/ampere-hour. No perfluorinated
product corresponding to the starting material was evident in the
product.
EXAMPLE 12
Electrochemical fluorination of 1,1 BIS(METHYL SULFONYL BUTANE)
This was fluorinated as in Example 1 at an average of 11 amps, an
average of 5.7 volts, 0.034 to 0.068 MPa (5 to 10 psig), and
25.degree. C. to 30.degree. C. Perfluoromethanesulfonyl fluoride
was produced at 62% theo. or 0.22 g/ampere-hour. The other desired
material C.sub.4 F.sub.10 was made at about 48% theo. or 0.136
g/ampere-hour.
EXAMPLE 13
Electrochemical fluorination of BIS(6-HEXYL SULFONYL)METHANE
This was electrochemically fluorinated as in Example 1 with the
addition of dimethyl disulfide as a conductivity additive (5 wt %
of the feed material). The solid feed material was dissolved in HF
and fed to the electrochemical fluorination cell in a
semi-continuous manner over a period of 81.5 hours, while running
at an average of 20 amps, an average voltage of 6.3, at 0.21 MPa
(30 psig) control and an average temperature of 55.degree. C.
Cleavage of the molecule was the predominant reaction with C.sub.6
F.sub.14 being the major product formed at about 40% theo. with
C.sub.6 F.sub.13 SO.sub.2 F formed at about 20% theo. and
perfluoromethanesulfonyl fluoride formed at 10% of theo. Small
amounts of the perfluoromethyl-hexyl sulfone were also found.
EXAMPLE 14
Electrochemical fluorination of BIS(8-OCTYL SULFONYL) METHANE
This was electrochemically fluorinated as in Example 1 with the
addition of dimethyl disulfide as a conductivity additive (5 wt %
of the feed material). The cell was operated at an average of 20
amps, an average of 6.5 volts, 0.21 MPa (30 psig) control and an
average temperature of 55.degree. C. Yields of
perfluoromethanesulfonyl fluoride were about 5% to 10% theo. with
C.sub.8 F.sub.17 SO.sub.2 F produced at <10% theo. and C.sub.8
F.sub.10 being the major product formed during the 84.4 hour
run.
EXAMPLE 15
Electrochemical fluorination of ETHYL METHANESULFONATE
This was electrochemically fluorinated as in Example 1 with the
addition of LiF as a conductivity additive (+1/4 wt % of the feed
material). The cell was operated at an average of 30 amps, at an
average of 7.5 volts, 0.17 MPa (25 psig) control and about
50.degree. C. Perfluoromethanesulfonyl fluoride was produced and
collected at about 58% theo average 0.218 g/1.0 ampere-hour and
COF.sub.2, C.sub.2 F.sub.6 SO.sub.2 F.sub.2, SOF.sub.4, CF.sub.3 H
and CF.sub.4, were other cleavage products from this feed. Neither
OF.sub.2 nor perfluoroethylmethane sulfonate were found in the
collected products.
EXAMPLE 16
Electrochemical fluorination of HEXYL-OCTYL SULFONE
This was electrochemically fluorinated as in Example 1 with the
addition of dimethyl disulfide as a conductivity additive (5 wt %
of the feed material). The feed material was dissolved in anhydrous
HF and fed to the cell semi-continuously. The cell was operated at
an average of 21 amps, an average voltage of 6.0, an average of
0.17 MPa (25 psig) and about 50.degree. C. over a period of 76
hours. During this short run the yields of C.sub.8 F.sub.17
SO.sub.2 F were about 10% theo., as were the yields of C.sub.6
F.sub.13 SO.sub.2 F. The yields of the perfluoroalkanes
predominated at about 25% theo. for both C.sub.6 F.sub.14 and
C.sub.8 F.sub.18.
EXAMPLE 17
Electrochemical fluorination of ETHYL ETHANESULFONATE
This was electrochemically fluorinated as in Example 1 with the
addition of LiF as a conductivity additive (1/4 wt % of the feed
material). The ECF cell was operated at an average of 28.5 amps,
6.3 volts average, and 0.21MPa (30 psig) control and about
55.degree. C. Perfluoroethane sulfonyl fluoride was produced at
about 10% theo. and perfluoromethanesulfonyl fluoride was produced
at <5% theo. The major byproduct was C.sub.2 F.sub.6 plus
SO.sub.2 F.sub.2 and COF.sub.2.
* * * * *